The present invention relates generally to electroerosion machining and more particularly to a method for the controlled withdrawal of a countersink or counterbore electrode in an electroerosion or spark erosion machine in the event of a short-circuit between the electrode and the workpiece.
Generally a working clearance must be provided between the electrode and the workpiece during electroerosion or spark erosion machining in order to prevent short-circuits from forming. However, if a short-circuit does occur, it must be eliminated by the relative displacement of the electrode with respect to the workpiece. That is the original clearance must be restored.
In an AGIEMAT III type electroerosion machine that is well-known is the prior art, when a short-circuit occurs the electrode is withdrawn by moving it in such a way that the electrode initially moves in the direction towards the center of the eroded opening in the working or XY-plane and is then withdrawn vertically from the center point and therefore from the opening in the Z-direction. The electrode must then again be inserted into the opening that is to be further eroded. The aforementioned operating procedure that is utilized in the prior art methods is time-consuming and suffers from the further disadvantage that, in some cases, the short-circuit cannot be eliminated sufficiently rapidly, whereas in other cases the short-circuit removal measure is dimensionally excessive, that is, in some cases the withdrawal section is longer than necessary to remove the short-circuit. Finally, this type of withdrawal movement cab be used in those instances where the shape of the eroded opening is complex because in some cases during the withdrawal procedure there can be physical contact or interference between the electrode and the wall of the eroded opening of the workpiece.